Apparatus for charging raw materials to melting furnaces



mvsu'ron RAGNAR I TANBERG BY i ATTORNEY.

WE Gmm R EWW? B N v. Ammm Tomv Rmmm Get. 10, 1950 Patented Oct. 10, 195

APPARATUS FOR CHARGING RAW MATE- RIALS TO MELEING FURNACES Ragnar Tanberg, Drammen, Norway, assignor to Drammens Glassverk, Drammen, Norway Application July 17, 1946, Serial No. 684,095 In Norway April 3, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires April 3, 1963 2 Claims.

The invention relates to an apparatus for continuous charging of raw materials to melting furnaces. The invention is especially intended for use in continuous charging'of raw materials to melting furnaces for the production of glass, but may also be applied to charging of furnaces of other kinds.

In such furnaces difficulties have arisen because the usually pulverulent charging material employed dusts badly when introduced into the melting furnace, and this dust deposits on the arch of the furnace and on other interior surfaces. This formation of dust also acts injuriously because the dust enters down into the burner openings of the furnace and from there down into the regenerative chambers, which are thereby injured. Another drawback in the charging with pulverulent materials in the manner previously used is that the materials will easily be spread out over the surface of the melting bath and thereby get in contact with the refractory lining of the furnace, which is badly corroded due to the content of flux agents, such as soda, etc., in the materials.

In using the apparatus. according to the invention the above-mentioned difiiculties are avoided at the same time as other advantages are also obtained. In using the apparatus the pulverulent charge is introducedinto the smelt in the furnace by being passed through a refractory pipe, preferably placed in the arch of the furnace, which pipe is mounted in such a way that it opens out in'such a short distance from the bath surface that the temperature in the furnace is sufficient to sinter together the charge before the latter leaves the refractory pipe, to such a degree that the charge becomes consistent so that it may be continuously conducted down into the smelt with a velocity corresponding to the melting of the charge through contact with the molten mass. By the passing of the charge down through the refractory pipe, the sintering together will increase evenly so that, when the outlet opening of the pipe is reached, the charge has acquired such a thicknss that it may be introduced into the smelt. The charge will hereby be much more rapidly heated to the melting temperature than when placed on top of the smelt, and the charge will not be spread out over the surface, and as a result thereof it can not get in contact with the lining.

In the use of the apparatus it is of particular importance that the charge is preheated, and preferably it should be preheated to such a degree that the sintering has already been partly commenced when the charge is introduced into the refractory pipe. The degree of preheating depends upon the kinds of charging materials and the temperature maintained in the furnace.

The preheating may advantageously be carried out by means of the waste heat from the furnace itself. The preheating will not alone cause the sintering required in order to produce a sufficient consistency to take place before the charge is moved out of the refractory pipe, but at the same time it is hereby obtained that a part of the carbonic acid in the lime admixture is driven out of the materials. The driven out carbonic acid will either escape through the pulverulent material in the pipe or in the furnace space after having left the pipe. When the charge reaches down to the bath it will therefore, to a certain degree, have a smaller content of carbonic acid, and it therefore reacts more easily in the bath to a flawless glass mass without glass blebs being formed therein. The charge for a glass furnace contains, as known, considerable quantities of carbonates, because it mainly consists of finely crushed lime, sand and soda in an approximate ratio of about 20% lime, 20% soda and sand.

In order to facilitate the formation of a consistent mass of the charge it is furthermore advantageous to add thereto small quantities of substances which increase the ability of the charge to sinter together, substances which by the influence of heat will cause the mass to be glued together.

Such substances must naturally be selected materials, such as feldspar or glass mass, which do not impurify the mass to be produced.

As it may occur that the charge adheres to the walls of the refractory pipe oneproceeds in one way of carrying out the invention in such a manner that the feeding of the charging material to the refractory pipe is carried out in such a way that along the walls of the refractory pipe there will be a layer of a material which is especially easily fusible, for example a layer of glass powder.

As will be understood it will be necessary when initiating the process or after a possible pause in the feed of materials, to take special measures before a consistent sintered mass, which may be continuously introduced into the smelt, has been formed.

In order to slove this problem, one proceeds, according to the invention, in the manner that in the empty refractory pipe there is introduced from above by means of a rod or possibly a cord a plate which approximately fills out the pipe. The plate is lowered so that it closes the opening of the pipe, whereupon the preheated and partly sintered charge is filled into the pipe. When the charge is sufficiently sintered together, the plate is pushed or dropped down into the bath. The plate may consist of refractory material which will float on top of the smelt. It is removed later on a suitable occasion.

In order to facilitate the understandin of the invention there is in the appended drawing by way of example illustrated an apparatus for the carrying out of the method.

The drawing shows in section a part of the furnace arch with the refractory pipe. I desi nates the furnace arch in which the refractory pipe 2 is mounted. 3 shows an annular charging hopper mounted according to the invention, which serves to apply an easily fusible material 4, such as glass powder, along the walls of the refractory pipe. The opening of the annular hopper may advantageously be quite small so that only small quantities will pass out at the time, eventually in such a way that the material will only pass out when the hopper is subjected to a slight shaking.

The charge itself is indicated at 5 and the increasin sintering, as the charge passes down, is illustrated by hatching. 6 designates the surface of the smelt. For the sake of illustration the charge is shown extending an appreciable distance down into the smelt. 1 indicates the plate with the supportin rod 8, which is used when the feeding of the charge is to be initiated. The rod 8 may eventually be attached in such a way to the plate 1 that the latter may be detached from the rod. Instead of a rod 8 one may also employ a cord of a material which will be combusted when it enters into the furnace space proper. In the drawing the refractory pipe is shown fixedly connected with the arch. In many instances it is advantageous to mount the pipe so as to permit of raising and lowering the same so that the distance of its lower opening end from the smelt may be adjusted. The refractory pipe may, furthermore, also be mounted in furnaces which are not provided with arch, in which case the pipe may be held fast above the surface of the smelt by means of different kinds of devices.

The invention is described above especially in connection with its use for the production of glass. It may, however, with advantage be applied to other processes in which a charge is to be fed to a smeltto different kinds of metallurgical processes, for example.

I claim:

1. Apparatus for charging pulverulent raw materials into melting furnaces comprising a vertically disposed refractory pipe of substantially uniform cross-section positioned above the bath in the furnace and having its lower end spaced upwardly a short distance from the surface of the bath whereby heat radiated from the bath will effect sinterin of the raw materials moving down said pipe before said materials leave the lower end of said pipe and an annular hopper at the upper end of said pipe arranged to discharge a film of readily fusible material between the raw materials introduced into said pipe and the inner surface of said pipe.

2. Apparatus for chargin pulverulent raw materials into melting furnaces comprising a vertically disposed refractory pipe of substantially uniform cross-section positioned above the bath in the furnace and having its lower end spaced upwardly a short distance from the surface of the bath whereby heat radiated from the bath will effect sintering of the raw materials movin down said pipe before said materials leave the lower end of said pipe, an annular hopper at the upper end of said pipe arranged to discharge a film of readily fusible material between the raw materials introduced into said pipe and the inner surface of said pipe, and an outwardly flaring upper extension for said pipe to provide a conical section, said annular hopper being positioned to discharge said fusible materials onto the inner surface of said conical section.

RAGNAR TANBERG.

REFERENCES CITED The following references are of record in the file of this patent:

Batchell Sept. 1, 1942 

